Expression items
In Filters, an 
Expression filter item excludes rows from the output table by filtering on values in a specified column.
Unlike Relation items, expression items never add rows to the output table. They can only produce an output with the same or fewer number of rows. An expression item is not a join operation.
Expression items can take constant values or Parameters.
The following logical operators are available:
- Contains (ci)
Case-insensitive whole string or substring match.
- Not Contains (ci)
Inverts the results of Contains (ci).
- Equals (ci)
Case-insensitive whole string match.
- Not Equals (ci)
Inverts the results of Equals (ci).
- Equals
Case-sensitive whole string match.
- Not Equals
Inverts the results of Equals.
- Exists
Includes all rows that have non-empty values for this column.
- In
Reverse whole string or substring match.
- Regex
Regex pattern match. Supports flags. For example:
/[ab]/i- Matches
Similar to Regex, but does not support flags. For example:
[ab]- Starts-With (ci)
Similar to Contains (ci), but only match starting at position 0.
- Starts-With (cs)
Similar to Starts-With (ci), but case sensitive.